This invention relates to a torque-balanced vibrationless rotary coupling for transmitting rotary motion without unwanted vibration into the spindle of a machine tool. More particularly, a drive member drives a driven member using flexible connecting loops which are connected tangentially and at diametrically opposite connecting points through a free floating ring. The coupling was designed for use with a micro-machinery system disclosed in Omega-X Micro-Machine Systems, U.S. application Ser. No. 860,053, by Donald M. Miller, filed Dec. 14, 1976. See page 16, line 28, through page 17, line 12, of this application for an explanation of how the rotary coupling (element number 178) is connected to the Omega-X micro-machining system.
Fine machining systems require special coupling techniques to connect a drive motor to a workpiece spindle so that only rotational motion is transmitted. For example, diamond turning machine spindles are presently being driven by long flat belts from remotely mounted motors. However, these flat belts are a source of vibration in that they are not of uniform weight or thickness throughout their length. Also, motor vibration can be transmitted to the spindle by the tension of the belt. Other vibrationless rotary couplings are disclosed in Mechanisms, Linkages, and Mechanical Controls by Nicholas P. Chironis (McGraw-Hill, New York, 1965) at pages 334 to 335. However, none of these designs provides the degree of isolation ncessary for the super accurate micro-machining system disclosed in the above cited patent application.